我正在使用Cloud 9开发一个简单的Rails应用程序。
每次运行应用程序时，我都会在Cloud 9浏览器中收到此错误
No application seems to be running here!
我研究了这个，我无法弄清楚为什么。我用了
rails s -b $IP -p $PORT
启动服务器。这是在应用程序的根目录中完成的。我已经安装了所需的所有Rails gems / bundle。
当我运行应用程序时，我在终端中收到一条消息说
my code is running at htttps://......... example
当我看到错误时单击链接。
这是我尝试启动服务器后终端的响应：
$ rails server –b $IP –p $PORT
Exiting
/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in `require': cannot load such file -- rack/handler/–b (LoadError)
from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in `try_require'
from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:16:in `get'
from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/server.rb:290:in `server'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:125:in `print_boot_information'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:75:in `start'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:80:in `block in server'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:75:in `tap'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:75:in `server'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands.rb:17:in `<top (required)>'
from /home/ubuntu/workspace/dublinapp/bin/rails:9:in `require'
from /home/ubuntu/workspace/dublinapp/bin/rails:9:in `<top (required)>'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in `load'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in `call'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/command.rb:7:in `call'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client.rb:28:in `run'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/bin/spring:49:in `<top (required)>'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in `load'
from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in `<top (required)>'
from /home/ubuntu/workspace/dublinapp/bin/spring:13:in `require'
from /home/ubuntu/workspace/dublinapp/bin/spring:13:in `<top (required)>'
from bin/rails:3:in `load'
from bin/rails:3:in `<main>'